Strontium is mainly extracted from Strontianite, the scarce carbonate mineral of the Aragonite Mineral group among the small number of strontium minerals. Strontianite has a formula reading SrCO3, and is reported to have a molar mass of 147.63 g. However, in Sr Cations, Barium can substitute Strontianite by about 3.3 % and calcium, up to 27 %

Chemical Formula SrCO3

Derivation of Name
In 1791, this mineral took after its locality, Strontium, in Argyll shire, Scotland, where the mineral was discovered a year back,

Occurrence
Strontianite is a scarce hydrothermal mineral created in low-temperature seams of limestone, chalk and marl or marlstone, in concretions and geodes. It is rarely found in hydrothermal metallic seams but is widespread in carbonatites. Most likely it crystallizes at or close to 100 °C. Its incidence in open vugs (Wiki Description small to medium-sized cavities inside rock that may be formed through a variety of processes) and seams, hint its crystallization at especially low pressures, most likely those equal to the hydrostatic pressure of ground water. Under fitting circumstances, it changes to Celestine SrSO4, and is found by itself as a variation of Celestine. The said two minerals are frequently found in alliance, along with Barite, Calcite, Sulfur and Harmotome( A rare Zeolite).

Source
It’s generally found in Strontian, North West Highlands (Argyllshire), Scotland, UK. Layers of natural material were found in gneiss. Other areas of the UK are the Brownley Hill Mine (Bloomsberry Horse Level), North Pennines, North and Western Region (Cumberland), Cumbria Nenthead, Alston Moor District, England.

Mineralogy
Trontianite, a rare carbonate mineral is also among the very few strontium minerals. It is rare to get its crystals, though larger sizes are not so rare, which are typically sold as samples. Usual variety has pointed tiny crystals in glowing collections or tufts. Still, it forms pseudohexagonal twins akin to aragonite's famed twin. For some time it was mined in Germany to get strontium, an element utilized as a coloring agent of fireworks and additional applications.